A spectroscopic study of the fluorination and defluorination reactions on single-walled carbon nanotubes

Abstract

The purpose of manipulating isolated single-wall carbon nanotubes (SWNTs), rather than bundles, has led to an active research in the field of the functionalisation of such carbon compounds. Different ways exist today to obtain some new soluble macromolecules from SWNTs. Here we focus on the fluorination functionalisation. As the solubility properties depend essentially on the functionalisation degree, it is important to develop reliable and simple methods to quantify this degree. The C n F stoichiometry of three different fluorinated SWNTs samples are determined with the X-Ray Photoelectron Spectroscopy (XPS). Then the evolution of the Raman spectra with the fluorination degree of these samples is discussed. An atomic force microscopy (AFM) study highlights the good solvation properties of the most fluorinated sample with a majority of isolated nanotubes being observed. Then we take advantage of these good solvation properties, combined with the possibility of recovering the pristine non-fluorinated nanotubes, to carry out surface enhanced Raman spectroscopy (SERS) studies of well-dispersed SWNTs. These studies put in evidence the bundle effect, which is due to the agglomeration of SWNTs into bundles. This effect can be readily observed by Raman spectroscopy.

Transition from single to multi-walled carbon nanotubes grown by inductively coupled plasma enhanced chemical vapor deposition

“…Figure 7 shows the high resolution scan of the C1s region on a sample of grown SWCNTs from 10 min of growth at 650 C. The spectrum has been fitted with three components; one at 284.4 eV attributed to sp 2 hybridized carbon, a second peak at 285.2 attributed to sp 3 carbon mainly from adventitious carbon from atmospheric contaminants, 13 and finally a peak at 286.8 eV encompassing oxides of carbon such as carboxyl and carbonyl moieties. 31 The XPS data shows predominantly graphitic carbon is present on the surface, in agreement with the Raman data presented earlier. There is a small amount amorphous or sp 3 hybridized carbon present on the surface, possibly from carbonaceous impurities or possibly defect sites along the CNT walls and end groups.…”

Pattern Formation on Carbon Nanotube Surfaces

“…There are various ways to fluorinate CNTs, including gas phase routes using atomic fluorine [5], F 2 gas [11], BF 3 vapor [12], and CF 4 plasma functionalization [13]. Fluorine coverage of single walled CNTs increases with increasing temperature, reaching a maximum coverage of C 2 F between 250 and 300 C [14,15].…”

Single‐beam pumped coherent anti‐Stokes Raman scattering on carbon nanotubes

“…The other important point that is worth noting is that, when one does Raman scattering experiments, the resonance is very sharp and therefore, it is somewhat difficult and even speculative to try to determine precisely any diameter distribution in a given sample. It remains that when Raman scattering is performed in the red range excitations, some attempts have been made to assign RBM bands to isolated tubes on one hand and bundles tubes on the other hand [10], even if one knows that they can be different in terms of diameters. Another important point is related to non-linear effects, more precisely stimulated Raman scattering effects.…”